Coax Cable Loss Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the cable's loss per 100 m and the run length.
- Read the total loss and power delivered.
How it works
Total loss (dB) = loss per 100 m × length ÷ 100; power delivered = 10^(−loss/10).
Worked example
13 dB/100 m, 20 m. 2.6 dB loss — ~55% of power reaches the end.
Common mistakes
- Loss rises with frequency — use the rated figure for your band.
- Ignoring connector losses, which add up.
Frequently asked questions
How much loss is too much?
Every 3 dB halves your power. Keep feedline loss low, especially at VHF/UHF and above.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.